This invention relates to a drawing unit for a fiber processing machine, particularly a regulated drawing frame for processing cotton and is of the type which has at least two consecutive roll pairs, each having at least one roll driven by its own electric motor and further includes an electronic control and regulating device connected to the electric motors.
In a known drawing frame of the above-outlined type, disclosed, for example, in U.S. Pat. No. 5,438,733, with each driven roll a freewheel backstop is associated for preventing a reverse rotation of the roll. Such an arrangement has been found to be operationally generally satisfactory. It may occur, however, that the electric motors--even if to a small extent--turn in the reverse direction in a non-uniform manner. In case the electric motor associated with the preliminary drawing zone turns to a greater extent in the reverse direction, than the electric motor associated with the principal drawing zone, a faulty draft in the sliver may occur.